1. Open your Mozilla Thunderbird.
2. Go to Tools > Account Settings.
3. Click Create a new account.
4. Choose Skip this and use my existing email.
5. Enter Your name, full Email address and Password , click Continue.
6. At Mail account setup configure screen,choose Manual config .
7. Select the type of incoming server : IMAP.
Enter the name of your Incoming and Outgoing mail server: mail. (enter your domain name) with Port number 143.
8. Username will be your full email such as firstname.lastname@example.org
9. Click on Re-test the configuration and Click Done.
10. Back to your Thunderbird main menu and go to Outgoing Server and confirm your Outgoing SMTP server.
11. Check the Use name and password box and assign your email account to the User Name
and select No for Use secure connection.
12. You may start using Thunderbird by clicking on the top left Get Mail button.